Loader equipment comes in many different forms. These include front-end loaders, skid loaders, loader tractors, and variations of each. Each type of loader has advantages and disadvantages, such that the different loaders are more or less appropriate for different environments and/or tasks.
The first loaders were probably loader arms attached to a traditional farm tractor. Farm tractors are adapted primarily for pulling and operating implements attached to the rear portion of the tractor. Farm tractors typically steer by changing the orientation of the front wheels relative to the body of the tractor in the same general manner that on-road automobiles steer. Some of these tractors have loader arms that can be attached thereto to enable the tractor to be used as a loader in addition to its other functions, like pulling and operating implements. Because these tractors are designed primarily for operating implements attached to the rear, the operator is positioned near the rear of the tractor with the engine in front of the operator. This provides the operator good views of any implement attached behind the tractor. This configuration however, also places the operator far away from any loader bucket attached to the tractor, with the engine of the tractor blocking view of the loader bucket while it is down. Despite this disadvantageous loading configuration, loader tractors like these are still very useful, due to their ability to perform both loader and implement control with a single unit.
For larger scale loading environments, front-end loaders are typically used. Large front-end loaders are designed with use of the bucket on the front as the primary function. These large front-end loaders are adapted for off-road environments and for moving and lifting large quantities of material. These large front-end loaders typically steer via articulation. Articulated steering splits the loader into a front portion and a rear portion joined by an articulation joint. The cab and operator are usually positioned towards the middle of the loader with the engine behind the operator. The cab and operator are also positioned relatively high above the ground, behind and above the loader arms.
While front-end loaders like these provide good large-scale loading capabilities, they can be difficult to maneuver in tight spaces. Skid loaders were developed to fill this gap. Skid loaders have wheels that are fixed in orientation and steer by moving the wheels on one side of the loader at a different speed and/or in the opposite direction of the wheels on the other side. This manner of steering allows the loader to “skid” the tires and spin the entire machine about a vertical axis to turn.
Recently, smaller articulated steering loaders have been developed. These smaller articulated steering loaders maintain the same general design as large front-end loaders by having a centrally located cab with the engine behind the operator and the loader arms and bucket positioned in front of the operator.